On April 28, Michael Porter wrote:
However, there are a couple of things to be considered at the time of a
valve job. One, which has not been mentioned in this context, is valve
guides. I would generally recommend replacing the cast-iron guides with
silicon-bronze-aluminum guides, and installing valve stem seals.
Mike - I agree with you entirely on this post. Bronze is the common
substance except in The Triumph Register we're recommending Copper bronze
alloy with seals on the inlets. Your speculation (?) that higher rpm rapidly
increases oil consumption is a known fact on Big Triumphs and our UK engine
guru, Chris Witor is a strong advocate of these units. I'd only add that
inlet valve seals are even more beneficial where a rocker boost oil feed is
used.
On the question of exhaust valveseats, The Register approves those offered
by A.E. who offer two types. The first is the 1000 series Austenitic - cheap
and cheerful but fairly low grade. The better option (in our view) is the
6000 series of wrought steel alloy, 13% high chrome and molybdenum but this
has a price tag. Worth it however because they should last far longer,
depending on how you drive the car and the distance travelled. My view is
that unless the car is a daily driver (and many of our Big Triumphs are not)
this is a once in a lifetime modification. Even so, on hard used engines,
there is plenty of evidence they are a far better bet than the Austenitic
variants.
John Mac
Book 1: http://www.toolbox.ndirect.co.uk/triumphbook
Book 2: http://www.toolbox.ndirect.co.uk/crocus
Triumph Over Triumph magazine: http://www.cyberware.co.uk/~chips11
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